The present invention relates to an aircraft digital audio system and, in particular, to a digital audio system comprising more than one audio equipment and more than one radio equipment.
In known aircraft audio systems, an operator, using a headset that transmits an audio message hears his own voice in the headset with a time delay less than approximately 20 ms from issuing the message, so that the radio that transmits the message to the outside sends back an “echo-message”, commonly known as side tone.
The reception of the side tone in the operator headset fulfills two functions: not confusing him (letting him hear his own voice as happens when not using the headset) and confirming that the audio message is being properly transmitted to the outside by the radio.
If the radio is not transmitting, the side tone is not sent back and its absence allows the operator to be informed of it.
Aircraft audio systems using local side tones to reduce the time spent by pilots to establish a radio communication are also known.
In known aircraft digital audio systems that manage more than one piece of audio equipment and more than one piece of radio equipment and have latencies greater than 20 ms in the sum of forward and return paths, the distribution of side tone from the radio does not allow the operator to speak without confusion because he hears his own voice delayed.
The present invention is directed to solving this problem.